Matt Fritz offers a set of free miniatures rules called Across the Alps. The rules are for recreating the Battle of Trebbia from 218 BC, when Hannibal crossed the Alps to face the Roman Army at the river Trebbia. The rules are easy to play, being designed for Matt’s students. There also is a link there to paper figures.
I just found a new blog written by a guy chronicling his efforts to build a 10mm Warmaster Dacian army.
Valiant Britons is Jim Wallman’s contribution to wargaming ancient british tribes in the pre Roman era. Its designed for 15mm figures, but he says that any scale will do. Like all of Wallman’s rules sets, it’s well done and makes me want to start painting the period immediately.